Will this law have to go back to congress and senate so they can assess a tax before implementation?
Nope, SCOTUS just redefined it as a tax and approved the mandate on that basis. A mega huge enormous stifling smothering tax at that.
If the GOP have the brains that God gave a goose, they will use it to really good advantage every time Obama claims to have lowered taxes on most people now, as, according to SCOTUS, he has imposed a huge tax on everybody who works for a living. So not only can they show that Obama lied big time when he adamently claimed this was not a tax when he sold us this turkey, he also lost his claim to have lowered taxes.
That's the icing on the cake actually. The big prize is in removing Obama's ability to use the Commerce Clause to do end runs around us and the people we elect to represent us.